Solving the VDI Storage Contradiction

While 2013 may not be the “year” of desktop virtualization, it is certainly a year where interest is increasing rapidly and real-world production deployments are beginning to occur. A key part of the success of a VDI project is the level of user adoption. If the user is provided a virtual desktop that performs as well as or better than their current desktop and allows them to customize it the same way as their current desktop, user acceptance will be very high. After all, who wouldn’t want a faster desktop that is automatically protected and upgraded?

To enable this type of capability, VDI administrators are implementing persistent desktops. The major challenge to this strategy is that persistent desktops require discrete storage space. The cost to allocate capacity to potentially thousands of desktops would make the ROI of the virtual desktop project untenable.

To work around the capacity requirements of persistent desktops, most VDI administrators leverage golden masters and linked clones to reduce capacity demands. This method creates a single desktop image for a group of users and then the image is cloned so that each user within that group can customize their desktop image to their specific personal needs and preferences. Only the unique differences between the golden master and the clone are stored.

As a result of golden masters and cloning, the capacity demands of persistent desktops are greatly reduced. Each time a cloned desktop is personalized, adds a unique application or simply creates data, storage space is dynamically allocated. Storage I/O, however, becomes a serious bottleneck as demands to dynamically allocate space to thousands of cloned desktops puts an unexpected burden on the storage infrastructure.

Many storage systems simply cannot support thousands of users tied to a single golden master and they must subdivide the allocation significantly. This increases management complexity since multiple desktop images need to be managed and maintained. It also increases capacity requirements as each of these additional golden master copies are stored.

Atlantis ILIO 4.0 addresses these challenges by leveraging in host RAM as primary storage for persistent virtual desktops. Shared storage is used only for backup and recovery. Essentially each virtual machine operates and stores its data in the RAM of the physical server it is hosted. The high read and write performance of RAM enables the very effective use of the golden master / cloning model. RAM is obviously an expensive storage medium so using it efficiently is important. The heavy use of cloning, thanks to the speed of RAM I/O, leads to a 95% reduction in storage capacity.

The speed of RAM does more than just enable maximum virtual desktop density, it also greatly improves the user experience. Atlantis Computing claims that virtual desktops will boot in 12 seconds, see instant application launches and incredibly fast desktop/outlook search (something that many VDI administrators previously disabled).

See a demonstration video here:

Since all the virtual desktop I/O traffic is local to its server host, and that I/O is in RAM, the shared storage system is freed up for other tasks. Its new primary role is to act as a replication target for ILIO to protect desktop data in case their host fails.

Also new in 4.0 is Atlantis ILIO Center that provides push-button, fully automated deployment of ILIO in less than an hour. The ILIO Center can deploy the product on hundreds of servers, across dozens of racks in parallel. It will also automatically calculate optimal virtual desktop density per host based on the available CPU and RAM. It will then automatically create the datastore. Lastly, there is a VMware vCenter plug-in for single point of management.

Storage Swiss Take

VDI deployments often seem like an endless contradiction. Administrators are looking for ways to provide the best possible user experience while still reducing costs. Persistent desktops are the key to happy users but cost containment pressures require the use of golden masters and cloning, which leads to performance problems and user rejection.

ILIO resolves the contradiction. By leveraging host RAM to provide maximum virtual desktop density and maximum performance, VDI project managers are able to satisfy user performance demands while proving that a virtual desktop project can reduce both operational and capital costs. ILIO deserves strong consideration as a compliment to any existing storage environment looking to maximize their VDI investment.

Atlantis Computing is not a client of Storage Switzerland

Twelve years ago George Crump founded Storage Switzerland with one simple goal; to educate IT professionals about all aspects of data center storage. He is the primary contributor to Storage Switzerland and is a heavily sought after public speaker. With over 25 years of experience designing storage solutions for data centers across the US, he has seen the birth of such technologies as RAID, NAS and SAN, Virtualization, Cloud and Enterprise Flash. Prior to founding Storage Switzerland he was CTO at one of the nation's largest storage integrators where he was in charge of technology testing, integration and product selection.

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Posted in Briefing Note

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